Infrared imaging is used for a variety of applications, including nighttime surveillance, target acquisition and tracking, and atmospheric imaging. Infrared imaging is typical done using a focal plane array (FPA), a device comprising material capable of absorbing radiation over a broad spectral band such as infrared, in the process generating electrical carriers (electrons or holes) within the material.
The material of the FPA is selectively doped to form an array of photodetectors. A bias voltage is applied to the material so that the array of photodetectors can transfer the electrical carriers generated by the incident photons into a pixilated image pattern of electrical currents. A read-out integrated circuit (ROIC) consists of control and readout circuitry and an array of input cells each attached electrically to an element of the array of photodetectors. The ROIC processes the currents generated by each photodetector and reads out their magnitude as a stream of currents, voltages, or digital bits.
Current solutions for target acquisition utilize an FPA to detect high speed laser pulses that are reflected by a target upon being illuminated by a laser designator. It is desirable in many instances to capture imaging information on the background of the target; current solutions require a separate FPA to capture this information. Thus, two “cameras”—one for capturing target image information, and another for capturing target-related background image information, are required. This solution is sub-optimal for various reasons including but not limited to: the extra work related to “aligning” both cameras, the extra expense of installing two cameras, and the added weight of the second camera, the latter reason being extremely detrimental for aerial devices (e.g., missiles) utilizing laser guidance systems.
Descriptions of certain details and implementations follow, including a description of the figures, which may depict some or all of the embodiments described below, as well as discussing other potential embodiments or implementations of the inventive concepts presented herein. An overview of embodiments of the invention is provided below, followed by a more detailed description with reference to the drawings.